1. Field of the Invention
The present invention relates to a mobile device positioning system and a method of operating the same, and more particularly to a mobile device positioning system and a method of operating the same that can reduce the power consumption of the mobile device.
2. Description of the Related Art
A related art mobile communication device (a “mobile device”), such as a portable phone, personal digital assistant (PDA), or other devices, must know its position in order to increase the efficiency of communications such as voice calls and other communications.
Related art mobile devices determine their own position by periodically transmitting data to inform a base station that manages a cell, to which the mobile device belongs, of its position. Then, the base station transmits position information according to the received data to the mobile device.
FIG. 1 is a block diagram illustrating the construction of a related art mobile device positioning system, including a position-information receiving apparatus 10 transmitting positioning data of the mobile device, and receiving the position information according to the transmitted data, and a position-information transmitting apparatus 20 judging the position information according to the data received from the position-information receiving apparatus 10, and transmitting the determined position information to the position-information receiving apparatus 10. In this case, the position information receiving deice 10 may be a mobile device, and the position-information transmitting apparatus 20 may be a base station.
The position-information receiving apparatus 10 includes a communication module 11 for data communications, a position-information module 12 generating and transmitting data for positioning of the mobile device to the position-information transmitting apparatus 20 through the communication module 11, and receiving the position information according to the transmitted data through the communication module 11, and a power control module 13 controlling the power supply to the position-information module 12 and the communication module 11 at predetermined intervals.
If the position-information receiving apparatus 10 continuously transmits data, its power consumption will be large. In order to reduce the power consumption, the power control module 13 controls the power supplied to the communication module 11 at predetermined intervals so that the position-information receiving apparatus 10 can transmit positioning data at predetermined intervals.
The position-information transmitting apparatus 20 includes a data-receiving module 21 receiving the positioning data transmitted by the position-information receiving apparatus 10, a position-information determining module 22 determining the position information of the mobile device according to the received data, a storage module 23 storing the determined position information, and a data-transmitting module 24 transmitting the determined position information to the position-information receiving apparatus 10.
FIG. 2 is a view explaining the operation of a related art mobile device positioning system. The position-information receiving apparatus 10 first transmits the position information generated by the position-information determining module 12 to the position-information transmitting apparatus 20 through the communication module 11 S10.
The position-information determining module 22 of the position-information transmitting apparatus 20 determines the position information according to the data received through the data-receiving module 21, and transmits the position information to the position-information receiving apparatus 10 through the data-transmitting module 24 (S20).
Thereafter, the power control module 13 of the position-information receiving apparatus 10 turns off the power supply to the communication module 11 (S30).
After the lapse of a predetermined time period, the power control module 13 turns on the power supply to the communication module 11 (S40), and the position-information receiving apparatus 10 and the position-information transmitting apparatus 20 perform the data transmission for positioning (S50) and the position information transmission according to the transmitted data (S60), respectively, in the same manner as the above-described operations S10 and S20. Thereafter, the position-information receiving apparatus and the position-information transmitting apparatus repeat the operations of the above-described operations S30 to S60.
In the related art mobile device positioning system as described above, a time interval for supplying the power to the communication module 11 is predetermined irrespective of the moving speed of the mobile device.
FIG. 3 is a view illustrating transmission time intervals at which the related art position-information receiving apparatus 10 transmits positioning data according to the moving speed of a mobile device. Even when the moving speed of the mobile device is changed to a first moving speed, a second moving speed, and a third moving speed over time, the time for turning off/on the power supplied to the communication module 11 is kept constant. In this case, when the power of the communication module 11 is turned on, the data for the positioning is transmitted.
In other words, on the assumption that times for turning off/on the power being supplied to the communication module 11 in periods of the first moving speed, second moving speed, and third moving speed are T1, T2, and T3, respectively, the relation among T1, T2, and T3 is T1=T2=T3.
However, the power consumption of the mobile device is increased due to the position-information receiving apparatus 10 transmitting data for positioning to the position-information transmitting apparatus 20 at predetermined intervals, irrespective of the moving speed of the mobile device.
For example, if the moving speed of the mobile device is low, the amount of positional change of the device per unit time is small, while if the moving speed of the device is high, the amount of positional change of the device per unit time is large.
Accordingly, even when the moving speed of the mobile device is low and thus frequent updating of the position information of the mobile device is not required, the power supplied to the communication module 11 is turned on/off at the same time interval as the case in which the moving speed of the mobile device is high, and thus the power consumption of the mobile device is increased, which in turn causes the use time of the mobile device to be reduced.
On the other hand, if the mobile device is located in a specified cell, it requests the position information from a base station that manages the corresponding cell. Accordingly, if a large number of mobile devices exist in the corresponding cell and simultaneously request position information from the base station, the base station cannot secure sufficient quality of service (QoS).
Japanese Patent Unexamined Publication No. 1999-298945 discloses a method for reducing power consumption of a mobile terminal whereby a base station measures the moving speed of a mobile terminal, and transmits a position registration period that corresponds to the measured speed to the mobile terminal, and the mobile terminal transmits a position registration message according to the received period. Although this reference discloses a power reduction method whereby the mobile terminal transmits the position registration message according to the period transmitted by the base station, it fails to disclose any detailed means for reducing the power consumption of the mobile terminal. In addition, this reference fails to disclose any scheme for securing sufficient QoS when plural mobile terminals simultaneously transmit the position registration messages to the base station.